The present article of Yochanan Afek is dedicated to one of the most frequent and important defensive ideas - perpetual check. Here is what the author has to say about the importance of this motif:
Move repetition is a common fashion of positional draw, preventing the stronger side from converting his material or evident positional advantage. Perpetual check is a particular case of a positional draw. The enemy king is chased by repeating checks from which he can find no hiding. The most frequent piece to inflict perpetual check is naturally the stronger one, the queen, as capable of covering, often on her own, a large part of the board. Nevertheless, the other pieces, except for the King and the pawn, have also starred in numerous combinations.ending up in perpetual check. The perpetual check is a common defensive device that may be seen in two main forms: The much more common direct chase of the enemy king or alternatively the less common and more sophisticated one: Forcing the opponent to settle for a perpetual check as the only defense against one's threat(s). Though a pretty common practice perpetual check has occasionally been overlooked, in the heat of the battle, even by experienced masters and grandmasters.
The article contains 14 games + 14 interactive tests.
As usual, in the game section, you can see how the actual games continue and later you can try to find what the players missed in the game. The questions are sorted by level of difficulty. You will be able to demonstrate the solution in the test section.
Here is one example:
This position was seen in the game Peter Leko - Michal Krasenkow. After 34...Nc2? 35.Bc4, White managed to quickly convert his advantage. Can you spot the saving resource which was missed by Krasenkow?